The major objective of this research is to elucidate the role of brain stem neurons, particularly those of the pontine reticular formation (PRF), in the control of visually elicited saccadic and smooth eye movements. More specifically, these experiments are designed to: a) plot the movement fields (the area of the visual field to which an eye movement can be made and alter the discharge frequency of a particular neuron) of PRF neurons; b) relate the size and direction of saccadic eye movements produced by stimulation of discrete areas of the PRF to the movement fields of units in this area; and c) determine the effects of small isolated lesions of the PRF upon the latency, accuracy and velocity of eye movements during saccadic and smooth pursuit tracking. In a broad sense, results of these studies will be important in attempts to describe the neural events which intervene between the central processing of sensory information and the central programming of motor outputs.